The present invention relates to a set changing device of a slitter-winder, comprising a pusher device for pushing completed wound fiber web rolls of partial webs cut with a slitter-winder and carried by carrier rolls forward from the winding-up section.
By means of the slitter-winder, the fiber web is cut in the longitudinal direction into parallel partial webs, which partial webs are wound on the winding-up section carried by the front and rear carrier rolls into successive rolls, that is, a set in the transverse direction of the fiber web. As a carrier roll may also be used a belt arrangement provided around two leading rolls, that is, a so-called set of belt rolls. Set change refers to a stage in roll manufacture at which, before starting new winding, the winding has to be stopped, the web cut at the winding-up section and the set, that is, the completed wound partial web rolls removed, and once new cores have been positioned in the winding-up section, the winding of a new set is started.
A problem with the winding-up sections known from the prior art is the reliable fastening of the tail of the partial web rolls being wound, that is, of each fiber web roll being completed. For fastening the tail of a fiber web roll being completed, that is, the tail end of a web being wound, has been used a method in which glue stripes are applied on the web before the winding-up nip and the glue stripes have been run almost completely inside the roll through the winding-up nip before stopping the winding-up section. The fiber web roll is in contact with both the rear carrier roll and the front carrier roll (or the set of belt rolls), whereby the glue is pressed fast in the winding-up nip between the rear carrier roll and the fiber web roll being formed. This causes a problem to the glue stripe that has passed through the nip at the stage when the completed fiber web rolls are pushed out of the winding-up section, because the glued web may open from the roll. With certain web grades, especially heavy grades such as board webs, an opening web causes splitting in the glue stripe area, that is, the glue no longer gives in but the surface layer of the web detaches with the glue instead of the glue stripe opening within the glued area. The split glue stripe will no longer adhere and the gluing thus remains incomplete for this part. The insufficient fastening of the web end may cause the tail to open partly or completely, which in turn causes problems in measurements and in the transport and further processing of the fiber web roll. A completely opened tail will cause problems in a high-rise store house of rolls, where rolls are kept in a vertical position in stacks of several rolls. On the other hand, when winding thin fiber web rolls, a problem may be caused by the pressing action of the nip, due to which the glue may be pressed through several web layers. Another known method is one where the set is lifted off the rear roll and following the cutting of the web, the set is swivelled on the front roll in such a way that the tails are pressed fast on the nip of the roll pusher. The problem with this method is that it takes up extra time and thus reduces the capacity of the cutter.
To solve this problem, a working solution as such is described in Metso Paper, Inc.'s earlier Finnish patent publication FI118762. FIGS. 2A-2D show diagrammatic side views of the winding-up section of the slitter-winder disclosed in the publication FI118762 at different stages of winding. FIGS. 2A-2D show diagrammatically a roll pusher 17, which is fitted in such a way that the tail glued to the roll 10 is wound fast on the surface of the roll in a controlled way by the pushing motion of the roll pusher 17. The roll pusher 17 is designed and fitted to move so as to provide an adequate cutting angle for the web against the cutting blade 15 during the pushing out. The roll pusher 17 is equipped with a guide part 17A by means of which a small roll can be pushed out of the winding assembly without a remover device of small rolls connected to the pusher and moved by a separate actuator. In the situation shown in FIG. 2A, the fiber web roll 10 is about to be completed and in FIG. 2B, the cutting blade 15 has been lifted to the cutting position adjacent to the rear carrier roll 11. In the situation shown in FIG. 2C, the completed fiber web roll 10 is pushed by the roll pusher 17 towards the top of the front carrier roll 18, whereby the cutting blade 15 cuts the web W. At the stage shown in FIG. 2D, the roll pusher 17 pushes the completed roll to the lowering device 19.
A problem with this solution is that the mass of the set is received by one row of press rolls in the pusher 17, which means that the tip of the pusher unavoidably becomes relatively thick in order for it to withstand the mass of the set. This results on the one hand in the roll 10 possibly escaping from the carrier rolls 11, 18 before the row of press rolls on the pusher presses the tail fast against the fiber web roll 10. Pressing the tail fast requires that the lowering device 19 is realized as an uphill-type device, for example, as an uphill tipper, where the pressing fast of the tail can be continued. In connection with new machines this is relatively easy to carry out, but in modernizations the conversion of the lowering device 19 into an uphill-type one substantially increases the cost of the product improvement. Furthermore, a single row of press rolls has been noted to mark the surface of the fiber web roll.